The White Sox did it and you can argue it was effective to a point, the Royals are planning to do it now through the All-Star game.
What is it?
A 6-Man pitching rotation!
Is this a good idea?
I personally would love to see teams do a 4 man rotation or even 3 but 6 just seems like overkill! If your guys need that much rest why have them in your rotation period. This to me is one reason pitchers of old were so dang good, Stamina!
Sure they may only last a few years but they racked up the wins because they could go the distance and were backed by great players.